As engineering plastics having excellent heat resistance, impact resistance, transparency and the like, polycarbonate resins are used in a wide variety of applications such as optical components, mechanical components, electrical/electronic components, automobile parts, resin glass and building materials. However, polycarbonate resins do not have sufficient weather resistance and there is a problem in that, when exposed to ultraviolet radiation, they are easily deteriorated due to the occurrence of molecular weight reduction, yellowing and the like. This weather resistance is problematic particularly for the outdoor use.
In order to improve the weather resistance of a polycarbonate resin, a method of adding an ultraviolet absorber to a polycarbonate resin has been employed. Examples of the ultraviolet absorber include conventionally known benzophenone-based, benzotriazole-based, triazine-based and cyanoacrylate-based ultraviolet absorbers.
However, in such a conventional method of adding an ultraviolet absorber, the ultraviolet absorber has a problem in terms of heat resistance in that it is thermally decomposed or vaporized due to the heat applied during resin processing (e.g., extrusion, injection molding) and this leads to a reduction in its effect and contamination of the processing facility. Further, in the outdoor use, there is also a problem that long-term weather resistance is not attained due to gradual vaporization of the ultraviolet absorber.
In this respect, as methods of inhibiting such vaporization of an ultraviolet absorber, the Patent Documents 1 to 4 disclose methods of copolymerizing an ultraviolet absorber. However, the weather resistance provided by these methods is still insufficient.